Goolarra has given you good information. I read your post saying, "I've been doing OK on Armour (as long as I chew it up), but needed to go as high as 300 mg to eliminate all symptoms." That made me also wonder why you are changing anything. There is an old saying, "If it ain't broke, don't fix it." If the large dosage itself bothers you, be aware that the dosage is irrelevant. Symptom relief should be all important.
It is illegal to sell any product that contains a measurable amount of T3 or T4 without a script. That being said, we all know the black market is alive and well.
20 mg of "porcine thyroid glandular" would be a very small dose (less than 1/3 grain) if it were comparable to "desiccated porcine thyroid". The implication is that there are 20 mg of T3 in it. T3 is measured in mcg...20 mg would be enough to kill you. So, the label doesn't even attempt to tell you how much actual T3 there is in it. And, it doesn't even mention T4. There are enough issues with consistency in prescription meds. I'd be wary of what's in a product considered a dietary supplement. Supplements are virtually unregulated.
I just think you have no idea what you're taking. One batch could contain no T3, and another might be loaded. Why do you want to give up Armour?
I am wondering why you think it contains no T3 at all. I recently started taking it, through my doctor, and because I have no thyroid at all I know I am getting some T3 or else I would not be functioning. Whether it is a full dose of 20 mg. I don't know for certain. I take 2 capsules per day since Tuesday - 6/2. I am still trying to work with it and may add back some Armour, which is a tricky thing to do as per the first post, which I am now going to respond to directly.
"Biotics Research...glandular products are prepared strictly from USDA inspected bovine and porcine tissues and are certified BSE-free. GTA-Forte II contains 20 milligrams of porcine thyroid glandular (T3) along with 10 milligrams of zinc and I milligram of copper which are not present in GTA."
We periodically are asked about supplements and their actual thyroid hormone content. The description above implies that it contains 20 milligrams of "porcine thyroid glandular" with "T3" in parentheses after it. The implication would seem to be that it contains 20 mg of T3, which, of course is impossible. 50 micrograms of T3 would be a hefty adult dose of T3.
It's tedious to try to research ingredients because everyone's just trying to sell it.
My best guess is that it contains no thyroid hormones. It's thyroid glandular tissue from which all T3 and T4 have been removed.
Don't throw your Armour away yet...